The present invention relates to enclosures for housing electronic components and other sensitive equipment.
In order to protect electronic components from the adverse affects of ambient environmental conditions, such components are often housed within enclosures that are environmentally sealed to prevent moisture and other corrosive or otherwise debilitating gases and liquids located outside the enclosure from reaching the components inside.
FIG. 1A shows an exploded perspective view of an exemplary, conventional enclosure 100 for housing electronic components. As shown in FIG. 1A, enclosure 100 contains a cover 102, a chassis 104, and a face plate 106. Electronic components (not shown) such as printed wire boards and individual electronic modules are mounted within or on chassis 104. Cover 102 is then mounted to chassis 104 to form a partial assembly that encloses the electronic components on five of the six sides of enclosure 100 (i.e., the top, bottom, left, right, and back sides). The remaining, front side of enclosure 100 is formed by mounting face plate 106 onto the front side of the partial assembly formed by chassis 104 and cover 102. Face plate 106 has apertures 108 that provide electrical access to the electronic components housed in enclosure 100.
FIG. 1B shows a detail of one corner of cover 102 of enclosure 100, FIG. 2A shows a top view of cover 102, and FIG. 2B shows a top view of the corner shown in FIG. 1B. As shown in the FIGS. 1-2, cover 102 has a generally U-shaped groove 110 running around the periphery of the top side of cover 102 along the left, right, and back sides of cover 102. Groove 110 is adapted to retain a deformable (e.g., silicone rubber or polymer) gasket (not shown) that runs along the entire length of groove 110. In particular, groove 110 is specifically designed such that the gasket will extend above the top surface of cover 102 along the entire length of groove 110. As such, when cover 102 is mounted to chassis 104, the gasket will be compressed by the mating surfaces of those parts to form a sufficiently tight seal between cover 102 and chassis 104 along the left, right, and back sides of the resulting partial assembly referred to herein as the chassis/cover sub-assembly. Moreover, the width of the groove is preferably slightly undersized compared to the size (e.g., width or diameter) of the gasket to provide a friction fit for the gasket.
Furthermore, it is desirable for the ends of the gasket to protrude beyond the front side of the chassis/cover sub-assembly at both ends of groove 110 to form a portion of the sealing configuration when face plate 106 is mounted onto the front side of the sub-assembly.
Ideally, during assembly of an enclosure, such as enclosure 100 of FIGS. 1-2, the gasket is inserted into the groove using only vertical force, making sure that the gasket extends beyond the front side of the cover on both ends of the groove. The ends of the gasket are then trimmed as necessary to achieve a desired amount of protrusion. The cover is then mounted over the chassis to form the chassis/cover subassembly, followed by the mounting of the face plate onto the front side of the chassis/cover subassembly.
In practice, however, an assembler might insert the gasket within the groove by applying both vertical and lateral pressure to the gasket, e.g., using a finger or thumb, from one end of the groove around the periphery of the cover to the other end of the groove. As such, assemblers tend to stretch the gaskets as they are inserted into the grooves, thereby creating strain in the gaskets. After the ends of a gasket are trimmed, the strain on the gasket may overcome the friction fit, causing the gasket to relieve itself (i.e., contract along its length). As a result, one or both ends of the gasket may pull back into the groove, thereby eliminating one or both of the desirable, front-side protrusions at the ends of the groove. The subsequent application of the chassis and face plate may then fail to appropriately seal the assembly. In particular, the resulting xe2x80x9cgapsxe2x80x9d in the enclosure can cause leakage failure for UL testing or other quality issues for the electronic components.